1. Technical Field
The present invention relates to a virtual image display apparatus, such as a head-mounted display worn around the head for use.
2. Related Art
In recent years, as a virtual image display apparatus that allows formation and observation of a virtual image, such as a head-mounted display, there is, for example, a proposed apparatus in which the retina of each eye is so scanned with image light that an image is projected onto the retina, and the apparatus has a see-through configuration that allows the image light, which forms a virtual image, to be superimposed on outside light that is light from the outside (see JP-A-2007-178941).
To project light that will form an image in an oblique direction, it is, for example, necessary to perform distortion correction in which distortion produced in a projected image undergoes trapezoidal correction or any other type of correction. In contrast, as a technology used with a scanning image display apparatus that performs image projection based on optical scanning, there is a known technology that corrects trapezoidal distortion by changing the amplitude of deflection in an image projection process (see JP-A-2007-199251), although the technology is not intended for a head-mounted display. In a head-mounted display, to perform image projection in an oblique direction, for example, from the ear or nose side, some type of correction is necessary to correct image distortion as in a typical image display apparatus. It is also conceivable to perform correction, such as trapezoidal correction, on an image based on signal processing in a unit that produces the image.
When trapezoidal correction or any other type of correction is performed on a projected image, a greater amount of correction in general results in not only a smaller projected image and hence lower resolution but also a larger unused, waste area. To produce a high-definition image, for example, it is therefore necessary to form a higher-resolution image. However, in a head-mounted display, which is particularly required to be compact and lightweight, the resolution provided by an image generator is limited. Further, in a head-mounted display, each component desirably has a simple structure because the apparatus needs to be compact and lightweight, and when image projection is performed based, for example, on optical scanning, the structure of the apparatus is preferably simple, unlike the apparatus capable of controlling complicated optical scanning described in JP-A-2007-199251.